Wood burning heaters, as well as those which burn coal, peat, animal manure, paper, etc. are probably about as old as mankind. In North America, for the past three decades or so, little interest has been shown in the burning of fuels, other than oil, for home heating. This lack of interest changed dramatically following the North American oil embargo of 1972-73 and the discovery that the supply of oil, whether in Canada or in the United States, is not unlimited but, in fact, is limited. Furthermore, over the past five years or so, since 1972, the price of fuel oil and oil-derived products such as gasoline has increased to the point where many persons are now actively considering the use of the well-known alternate energy sources namely, wood, coal, etc. There is also concern that such energy sources be efficiently utilized in well-designed heating units.
A specific problem which has beset some woodburning heaters in the past is the accretion of solid products of combustion in chimneys which educe smoke from stoves. Chimney fires are reasonably common and methods for avoiding the build up of combustible products in chimneys are required. It is well known that every winter a number of houses are destroyed and human lives lost because of fires originating in chimneys.